Document Scheduled Job Runs

[x1101]

Create base document for scheduled jobs.

I'd like to add descriptions to these going forward, but just getting the schedules documented in a single location is a start.

[oraNod]

Thanks @x1101 What about adding this to the maintainers file? https://github.com/ansible/ansible-documentation/blob/devel/MAINTAINERS.md

I think these details are more relevant to the folks who maintain the repo. Honestly, adding a small .md doc to the root seems like it might add clutter.

[x1101]

Good call @oraNod. I did this as a starting point, but I agree a random floating file is less useful, and likely more confusing, than adding it to MAINTAINERS.

Updated.